The wrong boss can also ruin your home life. Here's how to prevent it.

What would happen if, instead of overworked and burned out, workers had supportive managers who understood work is just one part of life? What if workers had more control over their schedules, and flexibility? A decade-long research study of work culture, work-life fit and health, funded by the National Institutes of Health, has found that workers in such supportive, flexible environments show half the risk of cardiovascular disease, significantly lower levels of stress, higher job satisfaction, and better physical and mental health. They sleep and exercise more, they're more likely to go to a doctor if they're sick, and they spend more time with their children.

Healthy workers, healthy work-life fit and “redesigned” work for more support and flexibility are key not only to living a good life, but to doing good business, argues researcher Ellen Ernst Kossek, professor of management at Purdue University. At the end are her tips on how to better manage work-life conflict.

Q: How would you describe the state of the modern workplace?

Ernst Kossek: Some companies have this “all in” culture, where people are expected to be available 24/7, and it's not sustainable. They're actually burning out their people. After the economic crisis, people feel lucky to have a job. And it's viewed as a sign of lack of commitment if you're not available 24/7.

It's a very U.S.-centric thing. We are probably among the most extreme on this. In other countries, there are times when you're not available, and it doesn't mean you're not a good employee.

Part of what companies need to do is talk about availability and time off, and view it as normal that people aren't available on weekends or evenings, unless there's a deadline or an emergency. Then they need to talk about what those are.

There's no reason why we can't redesign work -- have back ups, spread the responsibility for when emergencies do arise, so you're not calling the same person every night when the computer goes down.

I've done research on situations like this, where people feel they have what's called “low boundary control.” People are more depressed. They're more likely to want to quit their jobs, they have lower work-life fit. They are just unhappy.

Q: Surveys show many workers feel they have low boundary control. And in many companies, work-life fit, being happy, is often seen as more of a perk, or a side benefit to the real job.

Ernst Kossek: It shouldn't be. Companies should care a lot about this. Burnout costs companies a lot. Ill health. Substance abuse. Employees have much less energy for quality work. There's a cost to all this stress. You either pay for it with a constant churn of talent, or bad morale, or mistakes. So, don't think it doesn't cost you money, it does.

The best companies understand that employee relationships are a partnership. A lot of studies show that, while your top talent might not always join the company for work-life reasons, it is one of the number one reasons why people stay.

Q: You've been researching the link between work-life fit, workplace culture and health.

Ernst Kossek: We've known for some time that work-life conflict affects health. But, until recently, the research hadn't been very high quality -- or high quality enough that people would see this as something worthy of change.

So the National Institutes of Health, the Centers for Disease Control and Prevention, and others put together the Work Family and Health Network in 2005, and got some of the best minds in the field from different disciplines to study it -- organizational behavior, sociologists who study the culture of work, family researchers who are interested in how family dynamics affect work, epidemiologists and health researchers.

Just like there's randomized studies on cancer, with control groups to compare to test groups, these are some of the first randomized, organizational-level studies to look at the question: If you change the organization and change health resources, how does that affect workers and families?

Because how are you going to move policy if you don't have the science to back it up?

Q: What are you finding?

Ernst Kossek: There's a clear relationship between work-family conflict and the way work is designed

Workplace social support matters. Having a boss that understands that work-life issues are part of an employee's needs, and critical for not burning people out.

In our research experiment with Spartan grocery stores in Michigan, we trained some of the managers for 45 minutes to an hour on how to support employees' work-life needs. They began to offer emotional support and instrumental support, helping employees get the right schedule. They learned not only how to be creative, but how to be role models.

Think about it, if you work for a workaholic, you're not going to have work-life balance. If you train the whole manager group, we found that you change not just individual behavior, but the entire culture.

We asked them to set a goal of two weeks to change behavior. We found reduced depressive symptoms, improved job satisfaction, reduced turnover.

We also found schedule control matters, giving people a say in how to arrange work so they have more control -- over schedules, workload, timing, facetime culture, focusing on results.

Q: How does that impact health?

Ernst Kossek: We're finding increased risks for cardiovascular disease if you have a boss that's less flexible.

In our grocery store study, people sleep better, and their physical health is better if they have lower work-life conflict, whereas workers with high work-family conflict were more at risk for sleep challenges.

The network studies are also finding biological crossovers of stress. One study of hotel workers found if you're stressed, when you go home, you can spread those stress hormones like a virus to the rest of your family. Several of our studies show stress from work-life conflict is affecting the long-term health of families and the U.S. workforce.

Q: You've written a book called “CEO of Me” about people's “flexstyles.” What are some things a stressed-out reader can do to set better boundaries and have better work-life fit and better health?

Ernst Kossek: How you manage your work-life relationships is a function of three things:

Your identity in terms of what matters most to you. Are you work-centric? Personal life-centric? Or dual-centric?

How much boundary control you need over both family-to-work interruptions, and work-to-family interruptions.

Your own style of managing technology. Are you constantly blurring work communications with non-work? Or do you keep them separate?

They're really linked together.

1. Manage your boundaries in a way that fits with your identity and values.

Some people are Integrators, who are happiest combining their work and home lives. Others are Volleyers, who prefer switching back and forth. And others are Separators, who are happiest with firm boundaries between work and life.

What matters is being in control of boundaries in a way that fits your identity. So take some time to figure out how you best focus in both work and life domains.

2. Focus on what matters most to you. And if you find at the end of the day you aren't able to give your best self to your family or the parts of the job you love, then something's not working, and you've either got to reduce your workload, find a job that better fits you, or get help from your family.

3. Plan your time. Set blocks of time to focus on one domain or another, so you're not pulled in so many directions at once. Try not to work on weekends, and take nights off, for recovery.

4. Set boundaries around technology. Do simple things. If you're a separator, or volleyer, don't put your email on the devices you use to read the news.

5. Schedule time for relaxation. Exercise and relax in a way that doesn't involve technology.

6. Ask for help. Have family members, or substitutes go to things that really matter but that you can't be there for. It can be an opportunity to have grandmom, or a spouse or another family member there. We think we have to do it all by ourselves. And part of it, setting good boundaries, is to realize we can't be like Michael Keaton cloning himself in the movie, “Multiplicity.” We need to strategically manage our energy and time.

7. Use time buffers to manage transitions between roles. I've found that really helpful, not scheduling things back to back, and having one thing bleed into the next. Transition time, even 10 minutes, can make things a lot less stressful.